What is the treatment for Black piedra (fungal infection of the hair shaft)?

Treatment of Black Piedra (Fungal Infection of the Hair Shaft)

Oral terbinafine 250 mg daily for 6 weeks is the most effective treatment for black piedra, as demonstrated by successful clinical and mycological cure in documented cases. 1

Diagnosis and Clinical Features

Black piedra is a superficial fungal infection of the hair shaft caused by the fungus Piedraia hortae, characterized by:

• Hard, black nodules firmly attached to hair shafts
• Nodules that cannot be easily removed by sliding along the hair
• Microscopic examination reveals numerous asci and ascospores
• More commonly affects scalp hair

Diagnostic Approach

• Collect affected hair samples with nodules using scissors or plucking
• Examine crushed nodules under microscope with potassium hydroxide (10-30%) preparation
• Culture on Sabouraud agar to identify Piedraia hortae

Treatment Algorithm

First-line Treatment

• Oral terbinafine 250 mg daily for 6 weeks 1
  • Demonstrated efficacy in clinical cases
  • Leads to both clinical and mycological cure
  • In vitro testing confirms sensitivity of Piedraia hortae to terbinafine

Alternative Treatments

1. Oral itraconazole

   • Effective for superficial fungal infections including piedra 2, 3
   • Dosage: 200 mg daily for 2-4 weeks

2. Topical approach (for limited disease)

   • Shaving or cutting the affected hair
   • Application of antifungal shampoos containing ketoconazole 2%
   • Must be combined with oral therapy for complete eradication

Monitoring and Follow-up

• Clinical examination 2 weeks after completion of treatment
• Microscopic examination of any remaining or suspicious nodules
• Consider extended treatment if degenerated fungal elements are still present
• Follow-up at 2 months to confirm complete resolution

Prevention of Recurrence

• Avoid sharing hair accessories, combs, and brushes
• Maintain good scalp hygiene
• Consider prophylactic antifungal shampoo in endemic areas
• Educate patient about potential for recurrence and early signs

Important Clinical Considerations

• Black piedra differs from white piedra (caused by Trichosporon species) in appearance and treatment response 3, 4
• Mixed infections with both types of piedra can occur but are extremely rare 4
• The fungus creates a complex, well-organized structure with both sexual (ascospores) and asexual (arthrospores) reproduction methods 5
• Recurrence may occur if treatment duration is inadequate
• Black piedra is more common in tropical regions of South America and Asia 5

Treatment Pitfalls to Avoid

• Inadequate treatment duration leading to recurrence
• Failure to confirm mycological cure (not just clinical improvement)
• Relying solely on topical treatments without oral therapy
• Not addressing potential sources of reinfection (shared hair accessories)
• Confusing black piedra with other hair shaft nodules such as white piedra, pediculosis, or trichorrhexis nodosa

While the British Association of Dermatologists guidelines focus primarily on tinea capitis 6, the treatment principles for fungal infections of the hair can be applied to black piedra, with the understanding that the causative organism and specific treatment requirements differ.